Math & Science ⇒ space in formulas

[drowsy]

yes, but if your manuscript is 100 pages and
you use the default \thickmuskip=5mu plus 5mu,
how do you know which paragraphs to rewrite? It can get as large as 10mu
and you might not even notice it. I saw this in a couple of books.

Right now i am using
\medmuskip=2mu plus 2mu minus 1mu
\thickmuskip=3mu plus 2mu minus 1mu